Wednesday, September 11, 2019

South West Monsoon Withdrawal 2019

Posted Wednesday 11th September:

The following is quoted from the criteria for South West Monsoon withdrawal from IMD

Withdrawal of SW Monsoon a) Withdrawal from extreme north-western parts of the country is not attempted before 1st September.
b) After 1st September: The following major synoptic features are considered for the first withdrawal from the western parts of NW India.
i) Cessation of rainfall activity over the area for continuous 5 days.
 ii) Establishment of anticyclone in the lower troposphere (850 hPa and below)
iii) Considerable reduction in moisture content as inferred from satellite water vapour imageries and tephigrams.

Now, out of these criteria, we see the 850 level anticyclone getting (and started ) to  establish.
We also the the BB-11 stuck and persisting around M.P. due to resistance of drier air and upper anticyclone conditions.

The Water Vapor content from the North West areas has also started getting low as per satellite images.

Another important criteria not mentioned here is the reversal to Westerlies of the 200 hp Jet Streams. From the Monsoon Easterlies, the Jet Streams have to become Westerlies starting from the Northern regions of the Sub Continent on the change of season.
As of today, we see the Westerlies coming as South as 30N, an indication of commencement of the reversal process.

The parameters should be full y or properly met, which i calculate to happen in the next 5 days.
Hence, i expect the South West Monsoon to begin Withdrawal from West Rajasthan after 5 days (from 11th).

Decreasing rains in NW India.

 Rains to continue next 3 days in West M.P. Decrease in Saurashtra and remaining Gujarat .

Delhi hot . Mostly dry and light rains on Thursday/Friday in some parts.


After a gap, Mumbai will see increasing rains intensity from Thursday Night. Rains frequency will increase from Thursday Night into Friday and Saturday.
We will get rainfall increasing all along the North Kokan region.

1 comment:

Nimish Thaker said...

Thanks for the update Rajeshbhai. Depressing to read about more rains for Mumbai, what is going to cause these increasing rains over Mumbai and North Konkan?